It is known to link electrical appliances in a chain-like manner and cause the appliances to be switched remotely. This can be achieved either by remote control using radio signals, multiple wiring from a central control unit or by using a common power supply linking the appliances and at least one control lead with appropriate cooling of information along the latter with decoding devices at each appliance.
The solutions hitherto are not particularly suited to lighting systems particularly those for discotheques and the like where it is desirable that the number of conductors between each lamp is kept to the minimum and where preferably a standard three core cable is to be used for interconnecting the various lights.
In addition, previous solutions have tended to be dedicated to a particular number of appliances along the chain and any reduction or increase in the number of appliances would result in failure of the system to recognise the change. Again in installations such as discotheque lighting and the like it is desirable that the greatest possible flexibility is provided and where long strings of lights which are to be switched in sequence are required, this flexibility is of paramount importance.
It is therefore an object of the present invention to provide a lighting system and control unit therefor which can be applied to theoretically any number of appliances for switching the latter remotely and in which a reduction or increase in the number of appliances in the chain does not alter the ability of the system to cope and maintain full control.
It is another object of the invention to provide a system in which only three cables are required so that a standard three core cable can be used in which the live and neutral cables supply power to the appliances and the so-called earth cable is used to convey switching and control signals to the appliances. It is a further object of the invention to provide a system in which the appliances can be caused to switch in sequence beginning at one end or the other of the chain or selectively beginning at both ends of the chain simultaneously and moving in opposite directions towards the opposite ends of the chain.
It is a further object of the invention to provide such a system in which the switching speed is controllable and in which the switching sequence can be effected to begin from either or both ends of the chain, the switching rate in both directions being independently selectable.
It is a further object to provide a system in which a switching pulse delivered to one end of the chain of appliances can be returned (or reconstituted and returned) to the sending end after it has actuated the last appliance in the chain, or, some defined appliance.